The trabecular meshwork of th eye is a principal site of outflow resistance in the eye. Initial efforts have shown that the protein compositions of the cells in different quadrants of the trabecular meshwork in a single eye are not significantly different. There is also no discernible difference in meshwork between fellow eyes. Experiments have been started to determine if the cellular protein composition of the trabecular meshwork changes with age. Preliminary indications suggest that difference might be related only to the amount of a specific protein rather than different protein compositions. The trabecular meshwork is stretched in a glaucomatous eye. Trabecular meshwork cells from Rhesus monkeys have been put in tissue culture. These cells as well as a bovine cardiac pulmonary artery endothelial cell line, which serves as a model for Schlemm's canal cells, have been studied under conditions of stretch. The cells grown on silicone sheets have been stretched 10 percent and 20 percent over control conditions. Results indicate a very rapid phosphorylation of specific proteins on tyrosine residues. These proteins as well as subsequent changes in the cell composition are currently being investigated.